DESCRIPTION (provided by investigator): This revised R01 application requests support to study a significant and growing but understudied drug use problem, non-medical prescription analgesic use (NMPAU). We seek to shed new light on gender differences in the epidemiology of NMPAU and associated problems for both adolescents and adults. We propose to conduct secondary analyses of data from 2002-2005 National Surveys on Drug Use and Health (NSDUH). There are four specific aims. The first aim is to examine gender differences in the incidence and determinants of first NMPAU, including incidence trends, risk periods for initiation, and determinants of recent initiation. The second aim is to determine gender differences in the patterns, sequences, and correlates of multidrug use among non-medical prescription analgesic users (NMPAUs), including injection drug use, multidrug use, and the developmental sequence from first NMPAU to other drug use (eg, cocaine, heroin, and other prescription drugs). The third aim is to examine gender differences in the prevalence and correlates of NMPAU disorders and the other substance use disorders, including recent trends of NMPAU disorders. The fourth aim is to investigate gender differences in the utilization of substance abuse treatment services and of the perceived need for substance abuse treatment among NMPAUs, including the location of treatment services received, the primary abused substance for which treatment was received, the primary abused substance with perceived need for treatment, and barriers to treatment service utilization. These proposed analyses will add new findings to the literature regarding gender differences in the incidence, prevalence, and correlates of NMPAU and associated problems (sequence of multidrug use, injection drug use, abuse and dependence, patterns of service utilization, and barriers to service utilization). They will have important implications for early identification of NMPAUs, designs of prevention and treatment initiatives, estimates of treatment needs, and generating hypotheses for future research. Subgroups of NMPAUs with an increased likelihood of injection drug use, multidrug use, or drug dependence, and underserved NMPAUs will be identified for early prevention or be targeted to improve their access to substance abuse treatment services. Such findings will be vital to policy makers in predicting the potential burden of NMPAU-related problems.